Same patient, different setting: to what extent do mobility measures concur?

Stack, E., Pickering, R., Pressly, V., McElwaine, T., Frankel, J. and Roberts, H. (2008) Same patient, different setting: to what extent do mobility measures concur? Age and Ageing, 38, supplement 2, P.ii60.

Abstract

Objectives: to compare standardised mobility measures performed by people with Parkinson’s disease in their own homes and the hospital gait laboratory.

Background: It is argued that people with Parkinson’s disease (PD) perform differently in a gait-laboratory compared to their own home. Such a systematic bias (or context effect) could render laboratory- or clinic-based mobility assessment invalid. We evaluated to what extent mobility measures in contrasting settings concurred.

Methods: seventy-five people with PD completed the Timed Up and Go Test (TUG), a 3m walk, the Standing-Start 180 Degree Turn Test (SS-180) and two on-the-spot turns at home and in a gait-laboratory at the same time of day, within two weeks: setting order was randomised. From video, we calculated the 95% Limits of Agreement (mean difference between settings ± two standard deviations (SD)).
Results: participants (median Hoehn and Yahr stage 2.5) were reassessed after a mean of 7 days (SD 2). Mean performances and differences between settings were as follows. TUG: 18s, 1s; Speed: 0.8m/s, 0m/s; Stride Length: 0.5m, 0m; Cadence: 104 steps/min, 1 step/min; SS-180: 5 steps in 3s, < 1 step and < 1s; Spot 180: 6 steps, < 1 step; and Spot 360: 11 steps, 1 step.

Conclusions: differences between settings were small and typical of repeated assessment in only one setting. Differences rarely exceeded 19 steps/min (Cadence); 0.1m (Stride Length); 0.3m/s (Speed); and 2 steps (SS-180 and Spot 180), for example. Performance was similar in both settings and we found no evidence of a context effect

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Contributors

Author: H. Roberts

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